Offshore Croatia – Hunting ‘Big Oil’ in the Centre of Europe

Neil Hodgson*, Anna Marszalek, Karyna Rodriguez and Richard Wrigley.
Published in First Break, Volume 32, May 2014
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The Adriatic offshore hydrocarbon province lies below the shallow waters between Italy and Croatia on the northern margin of Europe’s Mediterranean Sea. Plio-Pleistocene fields in the north produce commercial biogenic gas from clastic reservoirs in both Italian and Croatian waters, while oil is produced from modest pre-Miocene carbonate fields in the Italian southern Adriatic. The hydrocarbon play-elements required for the trapping of oil in carbonate plays offshore Croatia include the development of the reservoir at carbonate platform margins, a competent top seal and the presence of mature source rock. However, until new 2D seismic data was collected in 2013, none of these factors could be reliably constrained. Here, we demonstrate that all these play-elements are indeed present and can be defined by new, long-offset seismic. Furthermore, we believe the oil play-systems offshore Croatia have potentially more robust, simpler and larger targets, and exploration risk that can be better addressed by seismic methods than on the proven Italian margin.

Hydrocarbon exploration history Hydrocarbon exploration offshore Croatia commenced with the Jadran-1 well, drilled in 1970, and two years later in 1973, the Jadran-6 well made the first discovery – the Ivana gas field. This initial success was in the shallow clastic gas play in the northern Adriatic. Since then, 135 exploration and development wells have been drilled offshore Croatia, compared to more than 1358 exploration and development wells drilled offshore Italy. Croatian exploration success continued with the discovery of eight gas fields in the northern Adriatic which are now on-stream. Exploration activity in the central and southern basins of Croatia mirrored the exploration initiatives offshore Italy and focused on the Cretaceous carbonate platform oil play. Whilst several wells have encountered oil shows, there have been no commercial discoveries yet. However, this same carbonate platform play has been targeted successfully offshore Italy, including the discovery of the Rospo Mare, Elsa, Aquila, Rovesti and Giove oil pools. Despite the generic similarities, the nature of the carbonate oil play offshore Croatia is significantly different from that on the Italian margin and requires high-quality seismic to successfully image the Triassic and delineate source kitchens, identify platform margin reservoirs, and support basin modelling to constrain the timing of charge. The lack of such high-quality seismic has hampered the otherwise valiant attempts to chase the Mesozoic carbonate oil play in the Croatian offshore. Therefore, in 2013 Spectrum acquired 14,700 km of long streamer 2D seismic data, which is tied to an 8000 km dataset of 2011 reprocessed Italian 2D seismic data…

Full article can be downloaded using the link below.
Hodgson, Marszalek, Rodriguez, Wrigley – Offshore Croatia – ‘Big Oil’ in the centre of Europe

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